COAL questions

It's trial and error. Seat the bullet long enough that you can see the lands marking the bullet. Then gradually seat the bullet deeper until the lands no longer mark the bullet. I prefer to seat .015" off the lands. Once this is determined I can hold a dimension from the tip of the bullet. And yes, every different brand and style of bullet will be different.

Basically I set the length of my ammo using the max allowed by the magazine and after making some dummy rounds check for OK function as this is what will fit. Unless you want to single load the said ammo as this way is usually too long to use the MAG, If so you then use the procedure outlined above. After that step I work up my load starting at 10% below max testing for best accuracy and showing no pressure signs. After that I might tweak the length by a small amount to see if things improve any.
Pushing the bullet in further on an already established round will raise the pressure but when setting the round up the 10% lower starting load will keep you safe while deciding what your max load is.

Measuring the COL is quick and easy. Measuring to the base of a seated bullet is not. It is simple math, but still.....

I wish all the bullet manufacturers would list the length of their bullets, because I like to know where the base of the bullet ends up when I am working up new loads. If I change bullets, and the base will not be seated deeper, I know I probably won't have to tweak my recipe much. If the base of the bullet will be seated deeper, I know I will have to start over - at the min charge.

The closest I have come to finding this data is on the JBM website.

http://www.jbmballistics.com/ballistics/lengths/lengths.shtml

You can get an comparator to put on your calibers if you want to measure to the projectiles ogive. I usually just start long and keep setting deeper till it spins freely.

I did a ransom rest test the one day varying the seating depths in 9mm. 20 rounds per each seating depth was used - 2 shot groups of 10 rnds each @ 25 yards. Ranging from an OAL of 1.06 to 1.15". The lower end of that averaged 2.9" groups. The high end of that averaged 1.6" groupings. So it did indeed seem to make a difference.

Goneshoot'n said:

Is it safe to say that unless the bullet is jammed into the lands, the further in it is seated, the higher the pressure is going to be upon firing?

Click to expand...

Pistol or rifle?

Rifles- Weatherby rifles have more bullet jump to reduce pressure. More free bore.

There is a 30-06 pressure test online showing lower pressure as the bullet is seated deeper into the case. But at a certain point, deeper seat , will then increase pressure.

There are so many variables and cartridges that results can be confusing.

45, 9mm, Etc -Deeper makes more pressure.

If you believe everything online https://forums.1911forum.com/showthread.php?t=444542

"This is from John Barsness of Handloader/Rifle Magazines."

Trying to reach the rifling by using a long col, with little bullet shank in contact with the neck, may not let powder start burning correctly. The feeding ramp may also make the bullet crooked .

I try to start here.

I seat the bullet as long as possible that will still fit in the magazine. Then I chamber a round. If it hits the lands I seat it deeper until it slides into the chamber. Then I go shoot a few. If I'm unhappy with the results I may try seating them deeper, but rarely do. MOST bullets shoot best close to or even lightly touching the lands. I MIGHT get a little better accuracy with them seated a little longer, but they won't fit the magazine and I don't want a single shot. I don't really worry about the actual length. Either they fit or they don't.

I like to load EGA 124 V2 bullets.
They set ~.208in. into the case... depending on case length.